1. Field of the Invention
The present invention relates to enhancement of the utility of fluidically actuated wrenches and particularly to enabling the maximum torque produced by such wrenches to be varied in stepwise fashion and/or to be displaced from the body of the tool to thereby enable the tightening of fasteners which would otherwise be inaccessible. More specifically, this invention is directed to improvements in fluidically operated tools and especially to the reduction in the size and weight of such tools and to the provision of the capabilities of varying the output torque provided by such tools and displacing the output member from the tool body. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
The present invention relates to that type of fluidically powered tool which has become known in the art as a "torque wrench". An example of such a prior art "torque wrench" may be seen from U.S. Pat. No. 3,745,858. The tool of U.S. Pat. No. 3,745,858 provides an output torque via a rotatable socket which is driven during each forward stroke of the piston in a hydraulic cylinder. The tool includes a lever arm which drives the socket in a first direction, the socket being mounted in a frame, and a ratchet mechanism which permits movement of the piston in the opposite direction, without applying a reverse torque to the socket, upon completion of each torque producing stroke. The piston rod extending from the power producing hydraulic cylinder is coupled to the rotatable socket by means of the lever arm and the hydraulic piston subassembly is pivotally coupled to the frame and to the lever arm. The frame of the tool will be coupled to a rigid member in order to provide a platform which may be reacted against.
Tools of the type depicted in U.S. Pat. No. 3,745,858 have had significant commercial success. However, prior art fluidically operated "torque wrenches" have a number of inherent characteristics which have served to limit the utility of these tools. Most significantly, the prior tools have been somewhat inconvenient to use due to their weight, size and shape. Many bolts which would desirably be tightened using a power operated wrench are located in pockets or under projections and thus could previously be reached only with a tool in the form of a comparatively thin lever. Interestingly, although "torque wrenches" have been available for many years, the typical machine designer continues to assume that all bolts will be tightened with a lever regardless of the size of the bolt or the magnitude of the torque which must be applied thereto to achieve the requisite tightening. As will be apparent from perusal of U.S. Pat. No. 3,745,858, it is simply impossible to engage a socket which is directly driven by patented tool with a bolt located under a projection or in some other similarly inaccessible location.
It is to be noted that there have been attempts in the prior art to address the problem of coupling a "torque wrench" to an inaccessible nut or bolt head. Thus, for example, it has been suggested to employ a torque link, sometimes referred to in the art as a "crowfoot", to couple the tool to the fastener. A "crowfoot" is merely an elongated member which will be mechanically fastened at one end to the wrench output socket and which will be provided, adjacent its other end, with a socket-shaped opening. While the use of a "crowfoot" is an inexpensive approach, it does not offer a satisfactory solution to the problem since the torque applied to the fastener can be somewhat greater than the output of the wrench and will vary with the angle between the "crowfoot" and the wrench. In most cases where a "torque wrench" is employed it is necessary that the fastener be tightened to a predetermined degree and thus the torque applied to the fastener must be known and controlled.
Another proposed approach to solving the problem of tightening difficult to reach fasteners, which has to date been employed only on mechanical wrenches of the type disclosed in U.S. Pat. No. 3,683,686, is to provide an extension comprising a series of gears mounted within a housing. While such a gear-type extension drive can be narrower than the wrench itself, and thus able to reach fasteners that the wrench could not reach directly, it is a comparatively expensive accessory which is heavy and thus difficult to use.
A further deficiency of prior art fluidically operated wrenches resides in their lack of flexibility. Thus, it has long been desired to provide a tool which can, as necessary or desirable, react "straight back" of the fastener or at various angles thereto without requiring special reaction adaptors of various size and shape. Similarly, there has been a long standing desire for the ability to change the maximum output torque capability of tools of the type being discussed. In the case of prior art hydraulic wrenches, a different tool was required for each application. This often resulted in the user purchasing a tool which was too big for many of the intended applications.
An additional deficiency of prior art hydraulic "torque wrenches", which was alluded to above in the discussion of U.S. Pat. No. 3,745,858, resides in the comparatively large size and awkward shape of the tool which has resulted from the utilization of a hydraulic actuator pivotally connected to and extended from a frame in which the output socket was rotatably mounted. Thus, there has been a further long standing desire in the art, predicated on the desire to enhance the utility of fluidically operated "torque wrenches", to make such tools more compact and to enhance their torsional rigidity. Also, especially in those cases where the tool is to be used to tighten difficult to reach fasteners, it is desired to have a tool to which attachments, such as extension drives, can easily be coupled. It would also be desirable to provide a tool wherein the hoses which deliver the pressurized operating fluid will be coupled to the same end of the body of the tool and thus less apt to impede use of the tool. In fact, for some applications, the use of a single hose coupled to the tool would be a highly desirable attribute. Present tools employ a pair of fluid supply hoses which are coupled to opposite ends of the actuator cylinder.